| 摘要 |
The optical unit has an infrared unit (11) with transmitting element or diodes (12) and infrared unit (14) with receiving diodes (15). In front of these units there are two optical bodies or quasi-Fresnel lenses (30,31), circular discs with a flat surface (36) and a grooved or ridged surface (32), the grooves being circular (33) and the surface slightly convex downward. The lens (30) forms a beam from the rays (13) and the lens (31) deflects the rays (16). These lenses are made from plexiglass, with a diameter of 20mm and a thickness of 2mm. |
